When formulating food or beverage compositions, it is frequently useful to add vitamins to round out the nutritional value of the product. Vitamins are either water-soluble (hydrophilic) or fat-soluble (lipophilic). It is a particular challenge to formulate fat-soluble vitamins (such as vitamins A, D, E or K) into aqueous-based products, such as health beverages.
One known approach for formulating lipophilic vitamins into aqueous solutions is to add hydrophilic side chains onto the lipophilic base molecule. By doing that, the hydrophilic-lipophilic balance (HLB) of the entire molecule can be adjusted toward water-solubility, making the molecule water-soluble. An example of such a water-soluble variant of Vitamin E (Tocopherol) is Vitamin E succinate polyethylene glycol (PEG) 1000 (also referred to as Vitamin E TPGS) which has the following formula:

Additional water-soluble variants of Vitamin E can be made by substituting other dicarboxylic acids (such as carbonic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, phthalic acid, glycolic acid, lactic acid, mendelic acid, citric acid and mixtures thereof) for the succinic acid. In addition, the polyethylene glycol component can be adjusted such that it contains from about 200 to about 2000 (preferably about 1000) subunits. Also, polyether materials other than PEG, such as polypropylene glycol containing from about 200 to about 2000 (preferably about 1000) subunits can be used. Further, the PEG and PPG compounds can be provided as monolaurate, monomyristate, monopalmitate or monostearate derivatives. Specific commercially-available water-soluble Vitamin E materials include Vitamin E succinate polyethylene glycol (PEG) 1000.
While these materials can be placed into aqueous solution, they do potentially raise microbial contamination issues. Specifically, upon storage, they can provide an ideal medium for the growth of yeast, bacteria and mold. That contamination issue must be addressed before the materials can be used in food and beverage products. One way to address the issue is to pack the materials aseptically. The additional processing required to do that makes such packaging very expensive. Another way to address the issue is to place broad spectrum preservatives in the solution. While those may be effective, it is preferable not to include preservatives in one component of a finished product, since they might not be optimal for use in the finished product or there might be a desire to formulate the finished product without preservatives. A third way to address this issue is to maintain the pH of the Vitamin E solution very low (i.e., between about 2 and about 4) This, however, causes acid hydrolysis of the Vitamin E, resulting in vitamin loss.